.TH "MQTTAsync_message" 3 "Thu Sep 13 2018" "Paho Asynchronous MQTT C Client Library" \" -*- nroff -*-
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.SH NAME
MQTTAsync_message
.SH SYNOPSIS
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.PP
.PP
\fC#include <MQTTAsync\&.h>\fP
.SS "Data Fields"

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.RI "char \fBstruct_id\fP [4]"
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.RI "int \fBstruct_version\fP"
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.RI "int \fBpayloadlen\fP"
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.RI "void * \fBpayload\fP"
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.RI "int \fBqos\fP"
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.RI "int \fBretained\fP"
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.RI "int \fBdup\fP"
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.RI "int \fBmsgid\fP"
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.RI "\fBMQTTProperties\fP \fBproperties\fP"
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.SH "Detailed Description"
.PP 
A structure representing the payload and attributes of an MQTT message\&. The message topic is not part of this structure (see MQTTAsync_publishMessage(), MQTTAsync_publish(), MQTTAsync_receive(), \fBMQTTAsync_freeMessage()\fP and \fBMQTTAsync_messageArrived()\fP)\&. 
.SH "Field Documentation"
.PP 
.SS "char struct_id[4]"
The eyecatcher for this structure\&. must be MQTM\&. 
.SS "int struct_version"
The version number of this structure\&. Must be 0 or 1\&. 0 indicates no message properties 
.SS "int payloadlen"
The length of the MQTT message payload in bytes\&. 
.SS "void* payload"
A pointer to the payload of the MQTT message\&. 
.SS "int qos"
The quality of service (QoS) assigned to the message\&. There are three levels of QoS: 
.IP "\fB\fBQoS0\fP \fP" 1c
Fire and forget - the message may not be delivered 
.IP "\fB\fBQoS1\fP \fP" 1c
At least once - the message will be delivered, but may be delivered more than once in some circumstances\&. 
.IP "\fB\fBQoS2\fP \fP" 1c
Once and one only - the message will be delivered exactly once\&. 
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.SS "int retained"
The retained flag serves two purposes depending on whether the message it is associated with is being published or received\&.
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\fBretained = true\fP
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 For messages being published, a true setting indicates that the MQTT server should retain a copy of the message\&. The message will then be transmitted to new subscribers to a topic that matches the message topic\&. For subscribers registering a new subscription, the flag being true indicates that the received message is not a new one, but one that has been retained by the MQTT server\&.
.PP
\fBretained = false\fP 
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 For publishers, this indicates that this message should not be retained by the MQTT server\&. For subscribers, a false setting indicates this is a normal message, received as a result of it being published to the server\&. 
.SS "int dup"
The dup flag indicates whether or not this message is a duplicate\&. It is only meaningful when receiving QoS1 messages\&. When true, the client application should take appropriate action to deal with the duplicate message\&. 
.SS "int msgid"
The message identifier is normally reserved for internal use by the MQTT client and server\&. 
.SS "\fBMQTTProperties\fP properties"
The MQTT V5 properties associated with the message\&. 

.SH "Author"
.PP 
Generated automatically by Doxygen for Paho Asynchronous MQTT C Client Library from the source code\&.
